This is a collaborative project between the Johns Hopkins Department of Psychiatry and the Genetics Division of Collaborative Research, Inc. (CRI). The purpose is to develop a suitable family resource and to begin a systematic search for genetic loci that may code for bipolar affective disorder. Evidence from family, twin, adoption and a few genetic linkage studies strongly suggests genetic transmission of bipolar affective disorder, but the genetic mechanism has been debated. Based on the available evidence, it is likely that multiple loci act independently or in concert to cause bipolar disorder. In order to search for the loci involve, three things are needed: 1) a sufficient number of affected families, ascertained through a proband with bipolar type I affective disorder with 2 or more sibs who have been examined and classified as affected and for whom immortal cell lines have been established: 2) a relatively complete RFLP map of the human genome, allowing a search for relevant loci over the whole human genome; and 3) methods of data analysis that take advantage of the resolving power of a human gene map. CRI is completing a systematic RFLP map for the human genome, and our consultants, developed that necessary "interval mapping" and "simultaneous search" methods for linkage analysis. In this project, the investigators from Johns Hopkins will systematically ascertain and examine 50 families with bipolar type I affective disorder (20 families will be ascertained through the University of Iowa.) and CRI will establish lymphoblastoid lines will be made available to interested investigators. CRI will also begin, when the map is ready or when candidate loci are identified, to test appropriate linkage hypotheses.